Abstract. The impact of open crop residual burning (OCRB) on O3, CO, black carbon
(BC) and organic carbon (OC) concentrations over Central Eastern China (CEC;
30–40° N, 111–120° E), during the Mount Tai Experiment in 2006
(MTX2006) was evaluated using a regional chemical transport model, the
Models–3 Community Multiscale Air Quality Modeling System (CMAQ). To
investigate these pollutants during MTX2006 in June 2006, daily gridded OCRB
emissions were developed based on a bottom-up methodology using land cover
and hotspot information from satellites. This model system involving daily
emissions captured monthly–averages of observed concentrations and
day-to-day variations in the patterns of O3, CO, BC and OC at the
summit of Mount Tai (36° N, 117° E, 1534 m a.s.l., Shandong Province
of the People's Republic of China) with high correlation coefficients
between the model and observations ranging from 0.55 to 0.69. These results
were significantly improved from those using annual biomass burning
emissions. For monthly-averaged O3, the simulated concentration of
80.8 ppbv was close to the observed concentration (81.3 ppbv). The MTX2006
period was roughly divided into two parts: 1) polluted days with heavy OCRB
in the first half of June; and 2) cleaner days with negligible field burning
in the latter half of June. Additionally, the first half of June was
characterized by two high-pollution episodes during 5–7 and 12–13 June,
separated by a relatively cleaner intermediate period during 8–10 June. In
the first high-pollution episode, the model captured the high O3, CO,
BC and OC concentrations at the summit of Mount Tai, which were associated
with OCRB over southern CEC and subsequent northward transport. For this
episode, the impacts of OCRB emissions on pollutant concentrations were
26% (O3), 62% (CO), 79% (BC) and 80% (OC) at the summit of
Mount Tai. The daily OCRB emissions were an essential factor in the
evaluation of these pollutants during MTX2006. These emissions have a large
impact not only on primary pollutants but also on secondary pollutants, such
as O3, in the first half of June over northeastern Asia. The model
reproduced reasonably well the variation of these pollutants in MTX2006, but
underestimated daily averages of both CO and BC by a factor of 2, when using
emission data from almost solely anthropogenic fuel sources in the latter
half of the observation period when field burning can be neglected.